Lamp base end contact



Dec. 29, 1953 R. A. KUEBLER LAMP BASE END CONTACT Filed Aug 2, 1951Inventor: Robert, A. Kuebler HIS Attor W ney i 'aiented Dec. 29, 1953LAMP BASE END CONTACT Robert A. Kuebler, Cleveland Heights, Ohio,assignor to General Electric Company, a corporation of New YorkApplication August 2, 1951, Serial N 0. 239,953

6 Claims. (01. 339-446) 'This invention relates to electric lamps andsimilar devices requiring bases having end contacts for makingconnections to the enclosed filament or electrodes. The invention ismore particularly concerned with the means for securing the lead-in wireof the lamp to the end contact and for achieving a firm electricalconnection thereto.

In the manufacture of electric lamps, particularly to household typeincandescent lamps, it has become standard practice to employ a base,usually comprising a metallic shell having its cylindrical surfacethreaded and provided with an end contact or eyelet insulated from theshell. This base is applied to the neck of the bulb and is secured to itby a cement or other suitable means. In order to provide externalcontact surfaces for energizing the filament of the lamp, one of thelead-in wires is connected to the side wall or shell of the base and theother is connected to the end contact or eyelet.

Although some attempts have been made in the past to connect the lead-inwires to the end contact or eyelet, and also to the shell, by mechanicalmeans such as crimping or wedging, such attempts have met withlimitedsuccess only, at least in the large volume household types oflamps. The general practice has been to use a metal which is readilysoldered, for the shell and the end contact, and to make the permanentconnection to the lead-in wires by means of a solder joint. Thissoldering operation presents certain difliculties, particularly whenperformed by the automatic machines used in the mass production ofincandescent lamps, and is a relatively costly procedure from thestandpoint of the time and maintenance required in connection with thesoldering mechanism.

The desirability of eliminating the soldering operation in themanufacture of electric lamps has lately been accentuated by reason ofthe high cost of readily soldered metals such as copper or brass.Concurrently, other metals such as aluminum have become available atrelatively low cost. Aluminum constitutes a good conductor and it has agood appearance without any additional treatment so that it provides ahighly desirable substitute for brass. Even though it is possible tosolder aluminum, this is a relatively costly and generally uneconomicalprocess, since cadmium is required in the solder material and theoperation is more critical.

An object of the present invention is to provide a new and improved endcontact or eyelet structure for the bases of electric lamps and 2similar devices, to which a lead-in wire may be connected without theuse of solder.

A further object of the invention is to provide a base for anincandescent lamp whereof the end contact or eyelet may be mechanicallyconnected to the lead-in wire.

A more specific object of the invention is to provide a screw type basefor incandescent lamps wherein the end contact is mechanically connectedto the lead-in wire so as to secure a firm and permanent electricalconnection having a neat appearance, and which is not subject toloosening and disengagement during the life of the lamp.

In accordance with the invention, the end contact of the base is shapedto the form of a thin disc having an outwardly turned flare or tubularextension through which the lead-in wire of the lamp is threaded.Considering the tubular flare or extension as made up of four quadrants,the term quadrant being used in the imaginary sense only, the lead-inwire is first caught between two diametrically opposite quadrants byturning one in on top of the other. Thereafter the two remainingdiametrically opposite quadrants are turned down inwardly one top of thefirst two. The lead-in wire is thus bent over and caught between thefirst two mentioned quadrants, which in turn are protected by the lasttwo mentioned quadrants, thereby providing a firm electrical connectionwhich is mechanically protected from external pressure or shock.

For further objects and advantages and for a better understanding of theinvention, attention is now directed to the following description andaccompanying drawings. The features of the invention believed to benovel will be more particularly pointed out in the appended claims.

, In the drawings:

Fig. l is a side-sectional view of a fragment of an incandescent lampprovided with a base embodying the invention.

Figs. 2 and 2a are side-sectional and plan views respectively of an endcontact of a base in accordance with the invention prior to the crimpingof the lead-in wire; Figs. 3, 3a and 4, 4a are corresponding viewsillustrating the configuration of the same contact after the first stepin the crimping operation, and after the final step, respectiveiy.

Fig. 5 is a pictorial view of a lamp utilizing a bayonet type baseprovided with end contacts constructed in accordance with the invention.

Fig. 6 is a side-sectional view of a modified end 3 contact constructionfor a base embodying the invention.

The general appearance of a screw type base in accordance with theinvention, and the internal construction and means for securing it tothe neck of a bulb, are shown in Fig. 1. The base i is mounted on theconstricted upper portion or neck 2 of an evacuated bulb of which afragment is shown at 3. The bulb may be of conventional construction andcontains a filament (not shown in the drawing) mounted within it on theends of the lead-in wires 4 and 5 which pass out of the bulb through apress 6.

The base proper comprises a threaded metal shell '5, an end insulator orweb 8, and an end contact Q constructed in accordance with theinvention. The insulating web 8 may be made of glass in accordance withthe common practice, or it may be made of a thermal setting plastic. Thebase is shown herein as fastened to the neck of the bulb by means of asuitable cement indicated at it, although it may equally well befastened mechanically by means of indentations in the neck of the bulband corresponding notches in the skirt of the shell 7. The contactsurfaces for the lead-in wires i and 5 are provided by shell and endcontact 9 of the base respectively. The lead-in wire is bent down aroundthe neck of the bulb and is out off at d, slightly beyond the pointwhere it emerges from under the skirt of the shell. The electricalconnection may be made through soldering at that point, or, if analuminum shell is used, the connection may be made by shaping the sealof the bulb such that the wire is squeezed between it and the insideedge of the 0 shell. This type of connection is described in thecopending application of Charles E. Beck, No. 244,753, filed September1, 1951, entitled Electric Lamp and Base Construction, and assigned tothe same assignee as the present invention.

The detailed construction of the eyelet 9 and the manner of fastening thlead-in wire there to may be seen more readily in Figs. 2 to 4. Theeyelet may be shaped out of any suitable sheet metal, for instancebrass, steel or aluminum. In a preferred construction aluminum isutilized for reasons which have been explained, and the presentinvention eliminates the use of solder which is particularly undesirablein connection with aluminum. The contact member is preferably formed bystamping and may be termed a disc having a flat portion 12 and anupwardly turned portion or tubular extension [3 about 'a generallycircular aperture. The tubular extension maybe of a diameter 2 to 5times the size of the lead-in wire 5, and its length or vertical heightmay-be substantially equal to its diameter. It will be understood thatthese proportions are given merely by way of illustration and that widevaria tions therefrom may be utilized. The contact member may be helddown onto the top surface of the insulating web by means of downwardlyprojecting portions, such as the inclined tabs i l, which becomeimbedded in the plastic material of the web. Alternatively the endcontact maybe secured "to the web by turning down'the outer rim of thefiat portion 12 and iinb'eddin'gi't directly in the plastic material.

As a'preliminary step in the crimping'operation for achieving thefinished'article, the lead-in wire 5 is cut off substantially flushwith, or projecting just slightly through, the open end of the tubularextension It as shown in Fig. 2. Then a pair of diametrically oppositelips in the form of quadrant portions I5 and it of the tubular fiare areturned down, as illustrated in Fig.;3, through a punching operation. Thelips thus formed are integral with the body of the eyelet or contactmember 9, projecting outwardly from the rim of the aperture and havingbent end portions overlapping one another and clamping the lead-in wire5 in between. It will be observed that the right hand quadrant l5 wascollapsed or turned down first, the lead-in wire 5 then bent over it,and the left hand quadrant It then collapsed over the first with thelead-in wire caught between them.

The shearing and turning down of the quadrant portions may be achievedby means of a punch i1 having a generally semi-cylindrical opening I8 inits lower face. The thickness of the punch I7 is preferablyapproximately of the outer diameter of the tubular flare 13. This leavesupstanding quadrant portions 58 and 2B of substantially the same size asthe quadrant portions l5 and I6 which have been turned down. In generalit does not appear necessary to make special provision for insuring thatone of the lips or quadrant portions [5 or Hi turns down before theother so as to catch the lead-in wire between them. This appears tooccur more or less automatically, either one or the other of theportions 15 and I6 turning down first whereupon the lead wire bends overthe one first to turn down, and the remaining member then turns downover it. However, if desired, one side of the opening or cavity is inpunch 11, may be cut in less steeply than the other so as to insure thatthe same quadrant portion is always turned down first. In the drawing,the right hand side it of the opening drops down slightly more than theleft hand side, thereby insuring that quadrant portion [5 is turned downunder portion [6.

The final step in the crimping operation is to turn down the remainingpair of lips formed by quadrant portions [9 and 29. This may be done, asillustrated in Figs. 4, 4a, by means of a punch 25 similar to the punchi! which has been described but turned at right angles to it on thevertical axis of the tubular extension i3. The semi-cylindrical cavity22 in this punch is somewhat deeper than that in the former punch ll,since quadrant portions is and 28 in this case will preferably merelyabut together medially on top of the previously turned down quadrantportions is and it. It will be appreciated that the result is amechanical connection of the lead wire to the eyelet wherein the end ofthe lead is clamped between the overlapped bent end portions of one pairof diametrically opposite lips, and in which the bent end portions ofthe other pair of lips overlying those of the first pair, preferablyabutting together medially thereover.

The end contact fastening which has been described is simple tomanufacture and provides a low resistance electrical connection which isvery firm and which does not work itself loose. The eventual looseningof the connection during the life of the lamp has always been the mainobjection to mechanically fastened connections on lamp bases. It isrealized that proposals have been made heretofore for mechanicallyfastening the lead-in wires into tubular extensions of the end contactssimilar to that which has been described herein, and that patents haveissued on such constructions. Iowever these proposals have generallyadvocated a tubular extension or flare having an internal diameter justslightly greater than the size of the lead-in wire, which was thencaught in the extension merely by squeezing in its sides. Thedisadvantage with this type of construction is that the lead-in wire isnot positively locked in place but is held merely by lateral pressure onits sides. Thus when a lamp having an end contact of such type isinserted in a socket, the socket spring member, exerts a direct pressureon the end of the lead-in wire, tending to force it back inwards'intothe base thereby breaking the contact and ruining the lamp. With thepresent construction on the other hand, the lead-in wire is first bentat right angles and caught between two of the quadrant portions of theextension, that is, between two metal lips. Any pressure exerted onthese quadrant portions or lips tends but to compress further thelead-in wire between them, and, far from breaking the connection, servesbut to make it more secure. Furthermore, the two remaining quadrantportions or lips which are turned down over the first two serve toprotect the connection against mechanical shock. They also serve to hidethe lead-in wire and to provide the whole with a neat and finishedappearance.

While the invention has been particularly described with reference to ascrew type base, it is equally applicable to a bayonet type base such asis illustrated in Fig. 5. The base 25 illustrated therein comprises astraight-walled metal shell 26 whereof the top end is closed by aninsulating web 21 in which are imbedded a pair of metal contacts 28 and29. These contacts may be of substantially similar construction to thatwhich has been described previously, only reduced in size, and theconnections to the leadin wires are made in the same Way.

In Fig. 6 there is illustrated an alternative construction of an endcontact or eyelet for a base. The eyelet 30 comprises a flat portion 3|,and a depressed bowl portion 32 from the bottom of which is extrudedupward a tubular extension or flare 33 similar to that which has beendescribed in connection with Figs. 1 to 4. The leadin wire may befastened to this eyelet in the same way as has been describedpreviously, namely by turning down opposite quadrants of the tubularextension, the first pair to catch the lead wire between them and thesecond pair to fold down on top of the first two. The eyeletconstruction illustrated in Fig. 6 has the advantage that asubstantially fiat surface without any projections is presented at theend of the lamp.

While certain specific embodiments have been shown and described, itwill of course be realized that various modifications therefrom may bemade without departing from the invention. Thus the types of bases towhich the contact member has been applied and in connection with whichit has been described, are provided by way of illustration only. Theinvention may evidently be used with other types of metallic contactmembers secured to an insulating portion and through which a lead wiremay be threaded for fastening thereto. The appended claims are thereforeintended to cover any such modifications coming within the true spiritand scope of the invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A construction providing connections for an electric devicecomprising a lead-in wire and a thin metal contact member, said memberhaving a generally circular aperture and two pairs of lips formedintegrally with the said member and projecting outwardly from the rim ofthe aperture, the lips of one pair having bent :outer end portionsoverlapping one another, said leadin wirebeing clamped between saidoverlapped portions, and the other pair having end portions overlyingthose of said one pair.

2. A base construction providing connections for an electric devicecomprising a lead-in wire, a base including an insulating portion and athin metal contact member secured thereto, said member having agenerally circular aperture and two pairs of lips formed integrally withthe said member and projecting outwardly from the rim of the aperture,the lips of one pair having bent outer end portions overlapping oneanother, said leadin wire being drawn out through said aperture andclamped between said overlapped portions, and the other pair having endportions overlying those of said one pair.

3. A base construction providing lead-in wire connections for anelectric device comprising a lead-in wire and a base including aninsulating portion and a thin metal contact member secured thereto, saidmember having a generally circular aperture and two pairs of lips formedintegrally with the said member and projecting outwardly from the rim ofthe aperture, the lips of one pair having bent outer end portionsoverlapping one another, said lead-in wire being drawn out through saidaperture and clamped between said overlapped portions, and the otherpair having end portions overlying those of said one pair and abuttingtogether medially thereover.

L. A base construction providing lead-in wire connections for anelectric device comprising a lead-in wire and a base including aninsulating member and a thin metal disc contact secured thereto, saiddisc having a generally circular aperture and two pairs of lips formedintegrally with the said disc and projecting outwardly from the rim ofthe aperture, the lips of one pair having bent outer end portionsoverlapping one another over said aperture, an opening in saidinsulating member leading to said aperture, said lead-in wire beingthreaded through said opening and said aperture and clamped between saidoverlapped portions and the other pair of lips having bent end portionsoverlying those of said one pair and abutting together mediallythereover.

5. An electric device comprising a bulb having lead-in wires projectingtherefrom, and a base fastened to said bulb and providing contactsurfaces for said wires, said base comprising an insulating portion anda thin metal disc, said disc having a generally circular aperture andtwo pairs of lips formed integrally with the said disc and projectingoutwardly from the rim of the aperture, the lips of one pair having bentouter end portions overlapping one another, one of said lead-in wiresbeing drawn through said aperture and clamped between said overlappedportions, and the other pair having end portions overlying these of saidone pair.

6. An electric lamp comprising a bulb having lead-in wires projectingtherefrom and a base fastened to the neck of said bulb, said basecomprising a metal shell, an insulating web closing the outer endthereof, and an end contact in the form of a metal disc secured to theouter face of said web, said disc having a depressed bowl portion and acentral generally circular aperture within said bowl portion, two pairsof lips formed integrally with said disc and projecting outwardly fromthe rim of the aperture within 7 said bowl portion, the lips of one pairhaving: bent. outer end portions overlapping onev another, one; of saidlead-in .wires. being threaded. through said; aperture and clampedbetween said overlapped. portions, and the other pair of lips'havingbent outer end portions overlying those of said one pair: and abuttintogether medially thereover;

ROBERT, A,

8. References v Cited in the file of this patent UNITED STATES PATENTSNumber Name Date 1,965,231, Gustin V July 3, 1934 FOREIGN PATENTS:

Number. Country Date 610,286 Great Britain v Oct. 13,1948

